North Korea has launched a medium-range ballistic missile on Wednesday which landed near Japan's territorial waters for the first time. This missile is the latest in a series of launches in defiance of UN Security Council resolutions.
Japanese Prime Minister Shinzo Abe described the launch as a "grave threat" to the island country and said that Tokyo "strongly protested".
On Tuesday, the US State Department had strongly condemned North Korea's missile tests and said that US was aware of the ballistic missile launches.
"We remain prepared to work with our allies and partners around the world to respond to further DPRK provocations, as well as to defend ourselves and our allies from any attack or provocation," said Julia Mason, a State Department spokeswoman.
According to reports, the main body of the missile landed in Japan's economic exclusion zone, escalating regional tensions that were already high after futile negotiations with North Korea regarding missile launches.
South Korea's Office of the Joint Chiefs of Staff said that the missile that landed in the Sea of Japan was launched from a region in South Hwanghae province at about 7:50 a.m. Seoul time (2250 GMT Tuesday).
The statement also said that the launch showed North Korean ambition to "directly and broadly attack neighbouring countries and target several places in the Republic of Korea such as ports and airfields".
The missile has been identifies as a Rodong-type medium-range missile that flew about 1,000 km (620 miles).
However, US Strategic Command argues that it has detected two missiles, one of which exploded immediately after launch.
Last month, South Korea and United States signed an agreement under which an advanced Terminal High Altitude Area Defense anti-missile system will be deployed in the South.